The new president called the fight against Al Qaeda a “national and religious duty.”

A terrorist car bombing killed at least 25 people in the southeastern port town of Mukalla hours after Hadi took the oath of office. Of the victims, 21 were soldiers, but a woman bystander was killed as well.

In Aden, west of Mukallah, armed civilians believed to be part of a separatist movement fought with government forces as well, residents told reporters.

Many towns in the south – including Zinjibar, have been attacked by the Al Qaeda terrorist group Ansar al-Sharia as government forces moved to join the fighting in the capital of Sana'a.

A Yemeni security official said the five terrorists died in the siege of Zinjibar, which began Saturday night. The shelling, which continued through Sunday, was aimed at wresting control of the southern town from Al Qaeda and returning it back to government hands.

One Yemeni soldier also died in the clashes when he stepped on a landmine east of Zinjibar, according to an official who spoke with reporters on condition of anonymity.

Meanwhile, former Yemeni President Ali Abdullah Saleh returned to his home Saturday from the United States. Saleh had been in the U.S. to be treated for injuries he sustained during an attack on his compound during last year's revolt against his government.